This invention relates generally to trucks or vans and more particularly to warning devices therefor.
A frequent and potentially dangerous problem can occur when a rear door of a vehicle such as a van or truck is left open. If the door is left open during transit, any cargo held in the vehicle can fall out through the rear door and damage cargo or, more seriously, injure other drivers. Several solutions have been proposed to warn the vehicle driver when the rear door is left open. One solution provides a mechanical arm that swings down from a rear side of the vehicle when the rear door is fully closed. An example of this type of warning device can be found in U.S. Pat. No. 3,924,558. In these mechanical warning devices, the arm typically includes a reflector or other highly visible portion which can be seen by the driver in his rear view mirror when the door is open. A problem with this mechanical approach is that the arm tends to take a lot of abuse with the opening and closing of the door as well as due to impact with cargo bays.
Another solution is to wire an indicator light up to the dashboard of the vehicle. The indicator light is then driven by a detector of some sort that detects when the door is open. Although this solves the reliability problems of the mechanical indicator, it suffers from several problems of its own. The first problem is that the indicator light must be installed in the dashboard of the vehicle. This can be a laborious process, typically requiring several hours of labor. This drives up the cost of the indicator system and, therefore, makes it less desirable. Another problem with this approach is that wiring must be run from the dashboard all the way to the rear of the vehicle. This can be problematic for vehicles that have separate, detachable trailers. In that case, a wiring harness of some sort must be used to allow the indicator light wiring to be connected and unconnected when the trailer is detached. This again increases the cost of this indicator. A further problem with this indicator system is that the indicator light can easily be overlooked in a busy dashboard. Typically, dashboards have a multiplicity of lights, dials and displays. As a result, the driver can come to ignore this indicator light amidst the noise of all the other devices in the dashboard.
One solution has been to add an audio indicator which buzzes when an open door is detected. The problem with this approach is that it presents a nuisance when the driver is unloading cargo and must have the rear door open. To deal with this nuisance the driver is forced to shut the vehicle off, which can cost the driver valuable time in restarting and warming up the vehicle.
Accordingly, a need remains for an open door warning system that does not suffer from the problems and limitations of the prior art.